1. Field of the Invention
The present invention relates to a positive resist composition. More particularly, the present invention relates to a positive resist composition which is sensitive to radiations such as ultraviolet rays (g ray, i ray), far ultraviolet rays including excimer laser and the like, electron beam, ion beam, X ray and the like.
2. Description of the Related Art
A composition comprising a quinonediazide compound and an alkali-soluble resin finds use as a positive photoresist because, upon exposure to light having a wavelength of 500 nm or shorter, the quinonediazide group decomposes to form a carboxyl group whereby the originally alkali-insoluble composition becomes alkali-soluble. Since the positive photoresist has much better resolution than a negative photoresist composition, it is used in the production of integrated circuits such as IC or LSI.
Recently, with the rise in the integration level of integrated circuits, the width of wiring in integrated circuits has become finer. To this end, etching is carried out mainly by dry etching in place of conventional wet etching. In the dry etching process, the shape of resist is directly reflected upon the shape of etched layer. If the shape of resist is not good, the etching can extend into the areas not to be etched and can make the formed integrated circuit defective or lower the product yield. For this reason, a resist good in profile is demanded today more earnestly than ever. Further, in the dry etching process, an elevation of substrate temperature can take place to cause a thermal deformation of resist pattern and a reduction of dimensional accuracy. For this reason, a high heat resistance of resist is demanded more earnestly than ever. When the currently used positive photoresists are checked from these viewpoints, they do not necessarily have the satisfactory profile, resolution, heat resistance, etc.